JP3882372B2 - Eddy current reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly uses an eddy current reduction device using a permanent magnet (hereinafter simply referred to as a magnet) for assisting a friction brake of a vehicle, and particularly when a fluid pressure system or an electric system during braking fails, the magnet support cylinder is not used. The present invention relates to an eddy current reduction device that facilitates return to a braking position.
[0002]
[Prior art]
For example, in a conventional eddy current reduction device that switches between braking and non-braking by rotating the magnet support cylinder forward and backward by the arrangement pitch of the magnet, the magnet support cylinder 16 made of a magnetic material shown in FIG. , 17 and a guide cylinder 4 made of a non-magnetic material, and a conductor that covers the outer peripheral surface of the guide cylinder 4 shown in FIG. A guide cylinder 4 having an inner hollow portion having a rectangular cross section has a large number of ferromagnetic plates 5 integrally coupled to the outer cylinder portion 4a at equal intervals in the circumferential direction. The magnet support cylinder 17 is supported. Magnets 6 and 7 that face the entire surface of the ferromagnetic plate 5 are coupled to the magnet support cylinders 16 and 17 by a support and bolts. The polarities of the magnets 6 and 7 facing the ferromagnetic plate 5 are alternately arranged in the circumferential direction. The guide tube 4 is supported by a non-rotating portion of the vehicle body, for example, a wall portion of a vehicle transmission, with a mounting flange 4d coupled to the left end.
[0003]
An actuator 22 a is supported on the left end of the guide cylinder 4 in order to rotate the movable magnet support cylinder 16 forward and backward by the arrangement pitch of the magnets 6. In the actuator 22a, a piston is fitted into a cylinder 23a, a fluid chamber is defined at both ends, and an outer end portion of a rod coupled to the piston is connected to the magnet support cylinder 16 via an arm. Pipes 34 and 35 for introducing pressurized air are connected to each fluid chamber of the actuator 22a, and pressurized air is introduced into one of the pipes 34 and 35 from a pressurized air tank (not shown) via an electromagnetic direction switching valve. Then, the magnet support cylinder 16 is rotated forward and backward by the piston, and the non-braking position in which the polarities of the magnets 6 and 7 facing the common ferromagnetic plate 5 are different, and the braking position in which the polarities of the magnets 6 and 7 are the same. Switch. When the rotating braking drum 2 crosses the magnetic field from the magnets 6 and 7 at the braking position of the magnet support cylinder 16, a braking force based on the eddy current is generated in the braking drum 2. The eddy current is converted into heat and dissipated to the outside. As shown in FIG. 7, the brake drum 2 made of a conductor such as iron is integrally formed with a heat radiating fin 2 b on the outer peripheral surface, and the right end portion is supported by a number of support arms 9 extending radially outward from the mounting flange 10. The The aforementioned eddy current reduction device is disclosed in Japanese Patent Publication No. 7-118901.
[0004]
In the eddy current reduction device described above, the magnet 6 of the magnet support cylinder 16 movable at the braking position is aligned in the axial direction with the magnet 7 of the magnet support cylinder 17 which is stationary, and between the magnet support cylinders 16 and 17 and the brake drum 2. Therefore, if a fluid pressure system or an electrical system fails during braking, it becomes difficult to release the braking. That is, the actuator 22a that returns the movable magnet support cylinder 16 to the non-braking position is difficult to move backward, and when the movable magnet support cylinder 16 remains in the braking position, the braking drum 2 is overheated. There is a possibility that the welded portion of the support arm 9 that supports the brake drum 2 to the boss portion 10 is broken and scattered to the periphery or the lubricating oil of the transmission is ignited due to overheating of the brake drum 2. is there.
[0005]
[Problems to be solved by the invention]
In view of the above problems, an object of the present invention is to provide an eddy current reduction device in which a movable magnet support cylinder automatically returns to a non-braking position when a fluid pressure system or an electrical system fails during braking. There is to do.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the structure of the present invention has a stationary guide cylinder made of a non-magnetic material disposed inside a brake drum, and the guide cylinder is provided with a number of ferromagnetic plates at equal intervals in the circumferential direction. A stationary magnet support cylinder and a movable magnet support cylinder, which are coupled to the respective magnets facing the respective ferromagnetic plates, are arranged in parallel in the axial direction inside the cylinder, and braking is performed by rotating the movable magnet support cylinder forward and backward. In the eddy current reduction device of the type that switches between the position and the non-braking position, the magnet of the movable magnet support cylinder at the braking position is slightly displaced toward the non-braking position than the magnet of the stationary magnet support cylinder. The magnet of the movable magnet support cylinder protrudes from the opposing ferromagnetic plate by the amount of deviation .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, in order to automatically return the movable magnet support cylinder to the braking position even if the fluid pressure system or the electric system fails during braking, the magnet of the magnet support cylinder movable at the braking position is Do not line up with the magnet of the stationary magnet support tube in the axial direction. Specifically, the magnet of the magnet support cylinder movable at the braking position is slightly shifted toward the non-braking position from the magnet of the stationary magnet support cylinder. That is, a rotational phase difference is provided between the magnet of the movable magnet support cylinder and the magnet of the immobile magnet support cylinder. As a result, if a fluid pressure system or electrical system failure occurs during braking, the restraining force of the actuator against the movable magnet support tube becomes weak, and the braking torque reaction force overcomes the restraining force of the actuator, so that the movable magnet support tube Is automatically returned to the braking position.
[0008]
【Example】
FIG. 1 is a left side view of a magnet support tube of the eddy current reduction device according to the present invention, and FIG. 2 is a plan view of the magnet support tube of the eddy current reduction device.
[0009]
In the present invention, in order to automatically return the movable magnet support cylinder 16 to the braking position even if a fluid pressure system or an electrical system fails during braking, the movable magnet support cylinder 16 is moved to the braking position. The magnet 6 should not be aligned in the axial direction with the magnet 7 of the stationary magnet support cylinder 17. Specifically, the magnet 6 of the magnet support cylinder 16 movable at the braking position is slightly shifted by the bias amount e toward the non-braking position (in the arrow y direction) from the magnet 7 of the stationary magnet support cylinder 17. In other words, a rotational phase difference is provided between the magnet 6 of the movable magnet support tube 16 and the magnet 7 of the stationary magnet support tube 17. Other configurations are the same as those of the conventional eddy current reduction device shown in FIGS.
[0010]
As shown in FIG. 3, the actuator 22a for rotating the movable magnet support cylinder 16 in the forward and reverse directions partitions the chamber 25a and the chamber 26a by inserting the piston 24a into the cylinder 23a, and magnetizes the rod 21a coupled to the piston 24a. It is connected to the support cylinder 16. When pressurized air is supplied from the pressurized air tank 62 to the chamber 26a through the electromagnetic direction switching valve 58 and the air in the chamber 25a is released to the atmosphere through the electromagnetic direction switching valve 58, the rod 21a is moved to the left together with the piston 24a. It moves to the direction and rotates by a value slightly smaller than the arrangement pitch of the magnets 6 and hits the stopper 28. The magnet 6 of the movable magnet support tube 16 is substantially aligned with the magnet 7 of the stationary magnet support tube 17 in the axial direction, and the polarities of the magnets 6 and 7 with respect to each ferromagnetic plate 5 are the same. A magnetic circuit z is generated between the brake drum 2 and the brake drum 2 based on the eddy current.
[0011]
When the electromagnetic direction switching valve 58 is energized, it is in the state shown in the figure. The electromagnetic direction switching valve 58 is excited in accordance with the state of a switch 51 that opens a circuit when the clutch pedal is depressed, a switch 52 that closes the circuit when the brake pedal is depressed, and a switch 53 that opens the circuit when the accelerator pedal is depressed. That is, the relay coil 43 is excited by the electronic control device 42 that controls the driving of the vehicle in the power battery 41, and the display 48 is displayed when the manual switching switch 44 disposed in the driver's seat contacts the contact 46. When the switch 51 and the switch 53 are closed (when the clutch is connected or the accelerator pedal is released), the pressure switch disposed in the pressurized air tank 62 via the diode 56 is turned on. The coil 65 is energized via 61. At this time, the contact piece 63a of the plunger 63 closes the contact 64 and excites the electromagnetic direction switching valve 58. During braking, when the air pressure in the pressurized air tank 62 falls below a predetermined value due to the failure of the fluid pressure system, the pressure switch 61 opens, and the coil 65 is demagnetized due to the failure of the electrical system such as the coil 65 being disconnected. Then, the plunger 63 is pushed back by a spring force (not shown) to open the contact 64 and close the contact 66.
[0012]
When the manual switching switch 44 is switched to the contact point 47, the indicator 49 is lit, and when the brake pedal is depressed, the switch 52 is closed and the exhaust brake 54 is also activated. At the same time, the current from the power supply battery 41 is energized to the pressure switch 61 via the switching switch 44, the switch 52, the normally-operated interlocking switch 55, the ACT switch 43a which is closed unless the relay coil 43 is excited, and the diode 57. Further, the electromagnetic direction switching valve 58 is energized through the contact piece 63a.
[0013]
As is apparent from the above description, when the switching switch 44 is connected from the open contact 45 to the contact 46, unless the speed change operation or the acceleration operation is performed, that is, the accelerator pedal is released, the electromagnetic direction switching valve 58 is simultaneously opened. When magnetized, the magnet support cylinder 16 is driven to the braking position. However, even during braking, the pressure switch 61 opens when the air pressure in the pressurized air tank 62 falls below a predetermined value, so that the electromagnetic direction switching valve 58 is demagnetized. Also, when a failure occurs in the electrical system, the contact piece 63a is opened and the electromagnetic direction switching valve 58 is demagnetized.
[0014]
As shown in FIGS. 1 and 2, during braking, the magnet 6 of the movable magnet support cylinder 16 is not completely aligned with the magnet 7 of the stationary magnet support cylinder 17 in the axial direction. The magnet 6 of the cylinder 16 is biased in the direction of the arrow y, that is, toward the non-braking position of the movable magnet support cylinder 16 by an amount of deviation e from the magnet 7 of the stationary magnet support cylinder 17. Even if 58 is demagnetized and pressurized air is not supplied to the chamber 25a of the actuator 22a, the actuator 22a loses the force to constrain the movable magnet support cylinder 16, and the magnet is supported by the braking torque reaction force exerted on the magnet support cylinder 16. The cylinder 16 is rotated in the direction of the arrow y, and eventually returns to the non-braking position where the polarity of the magnet 6 of the movable magnet support cylinder 16 is opposite to the polarity of the magnet 7 of the stationary magnet support cylinder 17 aligned in the axial direction. At this time, as shown in FIG. 5, a short-circuit magnetic circuit x is generated between the magnet support cylinders 16 and 17 and the ferromagnetic plate 5. Thus, the braking action of the eddy current reduction device is released, so that smooth vehicle operation can be continued.
[0015]
【The invention's effect】
As described above, in the present invention, the magnet of the magnet support cylinder movable at the braking position is fixed so that the magnet of the magnet support cylinder movable at the braking position is not aligned with the magnet of the stationary magnet support cylinder in the axial direction. Since the magnet of the magnet support cylinder is slightly displaced toward the non-braking position, and the magnet of the movable magnet support cylinder protrudes from the opposing ferromagnetic plate, the fluid pressure system and electric When a system failure occurs, the restraining force of the actuator with respect to the movable magnet support cylinder becomes weak, the braking torque reaction force overcomes the restraining force of the actuator, and the movable magnet support cylinder automatically returns to the non-braking position. Therefore, the magnet of the movable magnet support cylinder remains in the braking position, the braking drum becomes overheated, the braking drum becomes unusable, and finally the spoke welding that supports the braking drum on the boss part. This eliminates the risk of parts breaking and scattering around, or igniting the lubricating oil of the transmission due to overheating of the brake drum.
[Brief description of the drawings]
FIG. 1 is a left side view of a magnet support cylinder in a braking position of an eddy current reduction device according to the present invention.
FIG. 2 is a plan view of a magnet support cylinder in a braking position of the eddy current reduction device.
FIG. 3 is an electric / fluid pressure circuit diagram of the eddy current reduction device.
FIG. 4 is a perspective view of a braking drum of an eddy current reduction device to which the present invention is applied.
FIG. 5 is a perspective view of a guide cylinder and a magnet support cylinder of an eddy current reduction device to which the present invention is applied.
[Explanation of symbols]
2: Braking drum 2a: Inner peripheral surface 2b: Radiation fin 4: Guide tube 4a: Outer tube portion 4b: Inner tube portion 4d: Mounting flange 5: Ferromagnetic plate 6: Magnet 7: Magnet 9: Support arm 10: Mounting flange 16: Magnet support cylinder 17: Magnet support cylinder 21a: Rod 22a: Actuator 23a: Cylinder 24a: Piston 25a: Chamber 26a: Chamber 28: Stopper 41: Power supply battery 42: Electronic control device 43: Relay coil 44: Switching switch 45: Open contact 46: First contact 47: Second contact 48: Display rod 49: Display rod 51: Switch 52: Switch 53: Switch 54: Exhaust brake 55: Interlock switch 56: Diode 57: Diode 58: Electromagnetic direction switching valve 61 : Pressure switch 62: Pressurized air tank 63: Plunger 63a: Contact piece 64: Contact point 65: Coil 66 Contact

Claims (1)

An immovable guide cylinder made of a non-magnetic material is disposed inside the brake drum, and the guide cylinder is provided with a large number of ferromagnetic plates at equal intervals in the circumferential direction, and the guide cylinder is opposed to each of the ferromagnetic plates. An eddy current of a type in which a stationary magnet support cylinder and a movable magnet support cylinder for coupling a magnet to be obtained are arranged side by side in the axial direction, and the movable magnet support cylinder is rotated forward and backward to switch between a braking position and a non-braking position. In the speed reducer, the magnet of the movable magnet support cylinder at the braking position is slightly displaced toward the non-braking position from the magnet of the stationary magnet support cylinder, and the magnet of the movable magnet support cylinder faces the magnet. An eddy current reduction device that protrudes from the ferromagnetic plate that is displaced .

Images